Marine water storage systems typically use small tanks ranging from 5 to 20 gallons. The water in the tanks is heated to provided hot water on the ship or boat. When the ship is docked, the water normally is heated using a 110 or 220 volt electric heater. The electric heater includes low temperature and high temperature thermostats which turn the electric heater on and off, as required, to keep the water in the storage tank in a desired temperature range, normally 140-190xc2x0 F. When the ship is away from shore and shore power is not available, engine coolant from the engine is plumbed to the water storage tank and cycled through a heat exchanger so as to heat the water in the tank. The engine coolant can heat the water to a temperature equal to the engine operating temperature. Due to the small tank volume, it is common for the water temperature to reach 200xc2x0 F., or higher, with large diesel engines operating at temperatures of approximately 225xc2x0 F. Thus, very hot water of at least 200xc2x0 F. may be provided from the tank to the ship""s faucets and showers. Such hot water is a safety hazard.
Accordingly, a primary objective of the present invention is the provision of an improved marine water heater.
A further objective of the present invention is the provision of a marine water heater having a temperature control check valve to regulate the temperature of water in the tank.
Another objective of the present invention is the provision of a method for controlling the water temperature of a marine water heater.
Still another objective of the present invention is the provision of a method for controlling the flow of engine coolant to a marine water heater.
Yet another objective of the present invention is the provision of a check valve for controlling the flow of engine coolant to a marine water heater to control the temperature of the water in the storage tank.
A further objective of the present invention is the provision of a temperature control check valve for a marine water heater which is economical to manufacture, easy to install, and effective in use.
These and other objectives will become apparent from the following description of the invention.
The improved marine water heater of the present invention includes a water tank, a heat exchanger in the tank to heat the water in the tank, and a fluid line to supply engine coolant from an engine to the heat exchanger. A check valve is provided in the fluid line to regulate the water temperature. The check valve is moveable between open and closed positions to increase and decrease the flow engine coolant through the line, as the water temperature decreases and increases, respectively. The check valve includes a wax actuator which is in fluid communication with water in the tank. As the water temperature increases, the actuator expands to move the check valve toward the closed position. When the water temperature decreases, the actuator contracts to move the check valve toward the open position.
In the method of the present invention, the water temperature of the water heater is controlled by installing a check valve in the fluid line between a heat source and a heat exchanger in the tank. The method further includes the steps of exposing the check valve to water from the tank, and moving the check valve toward a closed position in response to increasing water temperatures and moving the check valve toward an open position in response to decreasing water temperatures. As the check valve moves between the open and closed position, the temperature of the water is regulated so as to remain within a safe range.